4-[(para-aminophenyl) alkyl] cyclo-hexylamine



Patented June 13, 1950 a v UNITED STATES PATENT OFFICE 3 4-[ (PARA-AMINOPHENYL)ALKYL1CYCLO- HEXYLAMINE Gerald M. Whitman, New Castle, Del., assignor to E. I. du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware No Drawing. Application December 4, 1947, Serial No. 789,761

e 2 Claims. (01. 260*563) 5 l 2 This invention relates to new compositions of sodium perruthenates, ruthenium halides, e. g'., matter and more particularly to new aromatic ruthenium pentafiuoride, ruthenium dichloride, amino compounds. trichloride and tetrachloride, ruthenium chloro- This invention has as an object a class of salts, potassium chloroperruthenate, ruthenium aromatic amino compounds, and more specifi- 5 sulfides, e. g., ruthenium disulfide and trisulfide,

cally new [(aminophenyl) alkyl] cyclohexylruthenium sulfate, and the like.

amines. Further objects reside in methods for Optimum results are obtained when the rutheobtaining these compounds. Other objects will niuin catalyst is in finely divided form. When appear hereinafter. it is desired to use low catalyst concentrations These objects are accomplished through the it is advisable to employ the catalyst supported production of the above mentioned cyclohexylon a carrier, e. g., charcoal, silica, kieselguhr,

amines by selective hydrogenation of one of the alumina, and the like. Such supported catalysts aromatic rings in a diaromatic diamine of the can be prepared by the method disclosed in U. S. general formula: Patent 2,079,404, or by other methods involving reduction of a compound of ruthenium in the R HN Ra- NHRi presence of a carrier substance.

The amount of ruthenium catalyst used may a 4 vary within the range of 0.002 to 10% by weight h ei R1 d R5 are of t group consisting of of the diaromatic diamine being reduced. The hydrogen atoms and alkyl radicals, R2 and R4 exact p ce a employed, however, depends are of the group consisting of hydrogen atoms upon the particular mp u d u d r in reand alkyl and alkoxy radicals attached to a carduction and 011 the tions Of hydrogenation. bon in the aromatic ring, and R3 is a saturated AS a rule t amount of Catalyst p yed W divalent acyclic hydrocarbon radical. Very from t 2.0%.

t b t method for carrying t t 5 In general the catalytic hydrogenation is efvention, a pressure reactor is charged with the feeted at a p atu wlthln the range of 80 diaromatic diamine and a ruthenium hydrogena- Satisfactory rates of reaction, it t catalyst, Th reactor is t pressured t amounts of catalysts within the limits indicated hydrogen t a pressure i excess of 1000 1 above as preferred, are obtained within the range in. and heated to between 80 and 275 C. After of 1 0 to 150C. and this is therefore the range an amount of hydrogen has been absorbed corre- Within which the Process is most generally 1 sponding to about 50% of the theoretical required a edto saturate completely the two aromatic nuclei, he hydrogenati S effected at Pressures the reaction is stopped, the contents discharged, above atmesphelic- :Generelly P u es in 8 the catalyst is removed, and the desired [(aminocess of 1000 1bs./sq. mare d d preferably phenyDalkyll cyclohexylamine separated by 15001bs./sq. in. to 20,000 lbs/sq. in. or more. The onv nti l me upper pressure limit is determined only by the The rea tion a b a i d t as b t structural limitations of the equipment employed operation or as a continuous or semi-continuous in effecting h hydrogenation. om the Sta dprocess, point of equipment requirements and reaction Because of their structural configuration, the rates at temperatures within the range p e y [(aminophenyDalkyll cyclohexylamines of this specified as vl9 1efefred the p ss most corninvention can exist either in the cis or trans only used will be from 1 500 to 3000 1bs./Sq-

isomeric forms. Hydrogenation of the corre- The hyd h q s efiected While the sponding diaromatic diamines leads to the fordlal'ematle diamlne IS 111 a fluid 0011611171011. 1 ti of a ixt re of the t is the diamine itself is a liquid or is in the form of Suitable ruthenium catalysts for use i th a solution in an organic solvent. Suitable orhydrogenation of the diaromatic diamines t ganic solvents are alcohols such as methyl, ethyl,

produce the [(aminophenyl) alkyll cyclohexyl- P py and the like, hydrocarbons Such s Y 0- amines of this invention are elementary ruthe- 5o h x n methyl cyclohexane, and the like, asoni m, ruthenium oxid s, rutheni sesquilines and other saturated aliphatic hydrocarbons, oxide, dioxide and trioxide, perruthenites, e. g., ethelS Slleh as h diethyl ether. nd t e barium perruthenite, ruthenates, e. g., potassium, like.

sodium, silver, barium, calcium, and magnesium In the second column of table below are listed ruthenates, perruthenates, e. g., potassium and [(aminophenyl) alkyl] cyclohexylamines produced upon hydrogenation of the diaromatic diamines enumerated in the first column.

for a period of 7.5 hours with stirring. No further hydrogen absorption was observed after the Diaroniatic Diamine [(AminophenyDalkyl] cyclohexylamine Bis(4-aminophenyl)metliane 1,2-Bis (4-aminophenyDethane 1,10-Bis(4-alninotolyl)decane 1,10-Bis (4aminoethylphenyDdecane Bis(para-amino methoxyphenybmethane Diaromatic diamines of the formula previously given, in which R3 is (CH2) n where n is an integer of from 1 to 12, are preferred. Other diaromatic diamines of this kind which may be hydrogenated to the [(aminophenyl) alkyl] cyclohexylamines of this invention are l,4-bis(para-aminophenyl) 2,2,3,3-tetramethylbutane, para, para'-diaminoditolylmethane, para, para-diaminodiphenetylmethane, para, para-diaminodianisylmethane, N,N' dimethyl(diaminodiphenyl)ethane, N,N' diethyl(diaminodiphenyl)methane, N ,N' di hexyl diaminodiphenyl) butane, para, para -diaminodiphenyldimethylmethane, para, para diaminodiphenylmethylmethane, and the like.

The examples which follow further illustrate this invention. Parts are by weight, unless otherwise stated.

Escample I Four hundred parts of bis(4aminophenyl)- methane was hydrogenated to 4-(p amino benzyl) cyclohexylamine in four equal portions in the following manner: One hundred parts of bis(4-aminophenyl)methane, 104 parts of purified dioxane, and 3 parts of ruthenium dioxide catalyst were charged into a pressure vessel adapted for agitation by shaking, the reactor was purged with hydrogen, heated to 100 C., and pressured to 1500-3000 lbs/sq. in. with hydrogen gas. After agitation for 1 to 1.5 hours under these conditions, the reactor was cooled, the contents discharged, the catalyst removed by filtration with the aid of activated carbon, and the following products isolated by distillation of the combined reaction mixture. The products obtained were as follows:

Fraction 1.Bis(4-aminocyclohexyl) methane; 66 parts; B. P. 131 C./1 mm.132 C./0.6 mm.; n 1.5059; neutral equivalent (hydrochloric acid, Methyl Red indicator) 105.5 (calc., 105.2)

Fraction 2.--Mixture of bis(4-aminocyclohexylmethane and 4(p-aminobenzyl)cyclohexylamine; 16.8 parts; B. P. 132 C./0.6 mm.-150 C./0.7 mm.; n 1.5362; neutral equivalent (hydrochloric acid, Methyl Red indicator), 132.4.

Fraction 3.4 (p-aminobenzyl) cyclohexylamine; 228.8 parts; B. P. 150 C./0.7 mm.-l62 C./0.8 mm.; M. P. 72.5-92.5 C.; neutral equivalent (hydrochloric acid, Methyl Red indicator), 197.2.

The remainder of the product consisted of unchanged bis(4-aminophenyl) methane.

Example II Twelve hundred fifin parts of bis(4-aminophenyl) methane, 3230 parts of purified dioxane, and 9.1 parts of a catalyst consisting of carbon impregnated with sodium ruthenate (corresponding to 0.63 part of ruthenium dioxide) were charged into a one-gallon autoclave equipped with a stirring device. After purging with hydrogen several times, the contents of the autoclave were heated to 200 to 215 C. and subjected to a pressure of hydrogen of 2500 to 3200 lbs/sq. in.

first 6 hours. The autoclave was cooled, the contents discharged, the catalyst filtered off with the aid of activated carbon, and the products isolated by distillation to yield:

Fraction 1.Bis(4-aminocyclohexyl) methane; 774 parts; 13. P. ll5.3 C./3 mm. C./4 mm.; n 1.5052; neutral equivalent (hydrochloric acid using Methyl Red indicator) 105.7.

Fraction 2.4 (p-aminobenzyl) cyclohexylamine; 234 parts; B. P. 140.8 C./0.9 mm.-162 C./1.1 mm.; neutral equivalent (hydrochloric acid using Methyl Red indicator), 204.9 (calculated 204.3).

The [(aminophenyDalkyll cyclohexylamines of this invention are useful in the manufacture of intermediates for the synthesis of dyestuffs since the aromatic amino group may be diazotized (following blocking of the aliphatic amino group, as by acylation) and the diazo derivative then coupled with a phenol, e. g., alpha-naphthol. The diazotization and coupling of bis(4-aminobenzyl) cyclohexylamine, prepared as described above, are illustrated below:

Seventy five parts of the isomer mixture of bis(4-aminobenzyl) cyclohexylamine (0.368 mole) were refluxed for 4 hours in 24.4 parts (0.41 mole) of methyl formate and 35.5 parts ethanol. The temperature of the boiling liquid rose from 68 C. to 77 C., where it remained constant for 1 hour. Most of the excess solvent was removed under vacuum to give a thick syrup which slowly solidified on standing. Two thirds (0.25 mole) of the N-(4'-(p-aminobenzyl)cyclohexyl) formamide thus obtained was mixed with 200 parts of ice in a one liter, 3-necked flask fitted with a stirrer, thermometer, and dropping funnel. The flask was cooled in an ice-salt bath and stirred, while a solution of 72 parts of concentrated I-ICI (0.729 mole) in 75 parts of water was added drop-wise maintaining the temperature at 8 to +6 C. To the milky suspension of hydrochloride thus formed there was added a solution of 17.8 parts (0.258 mole) of sodium nitrite in 35 parts of water. Addition was carried out under the surface and the temperature was kept at 0 to 5 C. The solution was kept cool in ice and added dropwise, under the surface, to a stirred mixture of 35 parts (0.246 mole) of a solution of alpha-naphthol in 10% sodium hydroxide (17.8 parts (0.45 mole) of sodium hydroxide in 166 parts of water) and parts of ice. Throughout the addition the temperature was kept at 0 to 3 C. by cooling in an ice-salt bath. After standing for 20 hours the thick suspension which formed was filtered, the product on the filter was washed with water, transferred to a vacuum desiccator and dried, yielding a porous, brick-red solid. The weight of product was 84 parts, which corresponds to an 38.5% yield.

The mixture of cis and trans isomers of 4-(p-aminobenzyl) cyclohexylamine, prepared as described previously, reacts with aldehydes to form Schiff bases which are adaptable to further chemical transformations. The preparation of such bases is described below:

Seventy six and five tenths parts of the cis and trans isomers of 4-(p-aminobenzyl)cyclohexylamine (0.375 mole) in 80.8 parts of ethanol was added drop-wise with stirring to 97.6 parts (0.8 mole) of salicylaldehyde in 646.4 parts of ethanol. After addition was complete the thick suspension of yellow crystals which formed was heated for 0.5 hour with stirring on a steam bath. The suspension was allowed to stand overnight, filtered, and washed on the filter with ethanol. After drying in vacuum the product was weighed. The yield was 148 parts which corresponds to a 96% yield. The product melted at 127 to 128 C. and analyzed 8.25, 8.12% nitrogen.

' From the mixture of cis and trans isomers, obtained in the hydrogenation of bis(4-aminophenyl) methane as described above, there may be separated the pure trans isomer by a procedure such as described below:

Five hundred and five parts of a mixture of the cis and trans isomers of 4-(p-aminobenzyl) cyclohexylamine, melting at 85-111 C., was dissolved in 610 parts of hot benzene under an atmosphere of nitrogen, 76 parts of petroleum ether (B. P. -75 C.) was added to the hot solution, the mixture allowed to crystallize under an atmosphere of nitrogen, the crystals filtered off by suction and washed with a cold mixture of 88 parts of benzene and 20 parts of petroleum ether to yield 395 parts (78.3% yield) of crude trans-4- (p-aminobenzyl) cyclohexylamine melting at 95-117 C. After six additional recrystallizations from hot benzene/petroleum ether in an atmosphere of nitrogen, there was obtained 277.5 parts (55% yield) of almost colorless trans- 4-(p-aminobenzyl)cyclohexylamine melting at 121.6-122.4 C. On distillation in vacuo, there was obtained 263.3 parts of diamine in the form of a white, crystalline solid; B. P. 173-176 C./- 0.8-1.2 mm. The diamine was further purified by a final recrystallization from benzene/petroleum ether under nitrogen to yield 222.8 parts of colorless product melting at 121.3-122.2 C.

Anal. Calcd. for C13H20N2Z C, 76.41; H, 9.86; N, 13.71; neutral equivalent (acetic acid/perchloric acid), 102.2. Found: C, 77.0, 76.96; H, 10.02, 10.03; N, 13.80, 13.77; neutral equivalent, (acetic acid/perchloric acid) 102.6, 102.3.

The ultraviolet absorption spectrum of trans- 4 (p aminobenzyl) cyclohexylamine resembles that for aromatic amines in general, exhibiting a peak at 2900 angstrom units (specific absorption coe'i'ficient in 95% ethanol, 3.48).

The trans diamine was characterized by the following derivatives: picrate, M. P. 217 C. (dec); c'iiacetyl derivative (dimorphic), u-form, M. P. 209.5-2l1.4 0.; fi-form, M. P. 224.2-225.3 C.

The mother liquor and washings from the first recrystallization of crude 4-(p-amin0- benzyDcyclohexylamine, described above, were concentrated on a steam bath under an atmosphere of nitrogen to a clear red syrup which crystallized on standing. The crystal cake was broken (under nitrogen), transferred to the filter with a small quantity of benzene/petroleum ether (50-50 by volume), and dried in vacuo to yield 34 parts (16.6% yield) of crude cis-4- (p-aminobenzyl)cyclohexylamine melting at 70.2-75 C. On further concentration of the combined mother liquor and washings, there was obtained an additional quantity of very impure cis 4 (p aminobenzyl) cyclohexylamine: 12.8

parts (2.5% yield); M. P. 55-64.5 o. The two fractions of cis isomer were combined and twice recrystallized from benzene/petroleum ether under an atmosphere of nitrogen to yield 76 parts of cis-4-(p-aminobenzyl)cyclohexylamine melting at 69-72 0.; this material was still contaminated by some of the trans isomer as evidenced by the wide melting point range.

a One hundred parts of pure trans-4-(p-aminobenzyDcyclohexylamine, prepared as described above, 104 parts of purified dioxane, and 3 parts of ruthenium dioxide were charged into a bomb mounted on a shaking device, the system purged several times with hydrogen, heated to 110 C. and pressured to 2-3000 lbs/sq. in. with hydrogen, and maintained under these conditions for three hours, with shaking. The bomb was cooled, the contents discharged, the catalyst filtered oil with the aid of activated carbon, and the product isolated by distillation. There was obtained 77.4 parts (75.2% yield) of bis(4-aminocyclohexyl) methane in the form of a colorless syrup which completely solidified on standing; B. P. 127.5 C./O.9 mm.-134 C./1.3 mm.; 11 1.5032; neutral equivalent, 104.8 (105.2 theory).

Conversion of the trans isomer, obtained as described above, to trans-1-amino-4-benzylcyclohexane and to trans-4-aminodicyclohexylmethane, which are of interest for further chemical transformations are described below:

To a cooled solution (16 C.) of 51.1 parts of trans-4-(p-aminobenzyl)cyclohexylamine in 396 parts of 25% hypophosphorous acid was added with stirring over a period of one hour a solution of 19.3 parts of sodium nitrite in 50 parts of water. After maintaining the solution at 2 C. with stirring for an additional 1.5 hours, excess nitrous acid was destroyed by addition of sulfamic acid, and a solution of parts of sodium hydroxide in 150 parts of water was added, whereupon a solid and an oil separated. Ether was added, the solid removed by filtration, and the filtrate extracted with two portions (71 parts) of ether, the ether solution extracted with r a solution of 99 parts of 12N. hydrochloric acid in 250 parts of water, the acid extract diluted to a volume of one liter, and the amine precipitated as an oil by addition of a solution of 80 parts of sodium hydroxide in 150 parts of water. The amine was freed from nonvolatile basic products by steam distillation, dissolved in benzene, extracted from the benzene solution with 150 parts of 3 N. hydrochloric acid, the amine liberated by addition of a solution of 40 parts of sodium hydroxide in parts of water, dried, and distilled to yield 20.4 parts (43.3% yield) of trans-1-amino-4-benzy1cyclohexane as a colorless liquid boiling at 105.2 C./ 1.2 mm.; n 1.5326.

Anal. Calcd. for CisHzsN: Neutral equivalent, 189.3. Found: Neutral equivalent, 188.9.

The amine was characterized by means of its acetyl derivative melting at 133.2-134.3 C., and by means of its picrate melting at 200-201 C.

A mixture of 25 parts of trans-l-aminoi-benzylcyclohexane, 129 parts of purified dioxane, and 1.25 parts of ruthenium dioxide catalyst was charged into a pressure vessel adapted for shaking and the mixture subjected to a temperature of 100 C. and a pressure of 2-2500 lbs/sq. in. for 2.5 hours. The pressure vessel was cooled, the product rinsed from the vessel with methanol, one part of Norit A added, the catalyst filtered off, and the product isolated by distillation to 75 yield 22.1 parts (85.7% yield) of trans-4-amino- 7 di'cyclohexylmethane as a colorless liquid boiling at 98 C./1.5 mm; 71 1.4870.

Anal. Calcd. for C13H25N: Neutral equivalent, 195.3. Found: Neutral equivalent, 195.1.

The amine was characterized by its acetyl derivative, melting at 139140.2 C., and its picrate. melting at l78.5-182 C.

The [(aminophenyDalkyl] cyclohexylamines of this invention, in addition to their value in the manufacture of dyestufi intermediates illustrated by the conversions described above, are also useful as intermediates for pharmaceuticals, germicides, rubber chemicals, surface-active agents, polyamides, polyamide-polyesters, corrosion inhibitors, etc.

As many apparently widely different embodiments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that I do not limit myself to 5 amine.

2. :1- (para-aminobenzyl) cyclohexylamine.

GERALD M; WIH'I'MAII.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date Kranz Mar. 6, 1939 OTHER REFERENCES Schopf et al., Ann.," vol. 448, pages 1-48 (1926).

Number 

1. A 4-((PARA-AMINOPHENYL) ALKYL)CYCLOHEXYLAMINE. 